For this purpose, one generally uses glass ampoules which are to be filed off or are frangible and, at the time of use, have an applicator end fitting made of a soft material attached to them. The frangible ampoules generally used have the drawback that their readiness to break remains limited; it may happen that glass fragments drop into the ampoule, which is to be avoided at all costs, especially when the contents of the ampoule are intended to be applied to the scalp. The so-called filing off capsules are even more difficult to handle and their readiness to break is also quite limited.
Moreover, the packaging of these ampoules in the factory requires very specialised equipment.
Furthermore, as has been indicated above, it is necessary at the time of use, to fit on to the ampoule an applicator end fitting made of a soft plastic material which must, on the one hand, avoid all risk of contact between the skin of the scalp and the ampoule which has been previously either broken or filed off, as the case may be, and, on the other hand, allow a drop by drop application by successive pressures on the said end fitting.
Finally, the glass ampoules constitute packaging units of a high final cost for a very limited ease of use.